GI embryology Flashcards
What do the liver, gallbladder and pancreas develop from?
diverticulum of the cranial half of the duodenum
What does the would-be liver look like in week 3?
In week 3, the liver appears as an out-pocketing of the future duodenum – hepatic diverticulum (liver bud)
What is the septum transversum?
future diaphragm
What do endodermal cells differentiate into?
hepatocytes (parenchyma) of liver
What are haematopoietic, Kupffer cells and connective tissue derived from ?
mesoderm of the septum transversum
What happens when the liver becomes too large to be contained within the septum transversum
It protrudes into the ventral mesentery
What does the protrusion of the liver do to the structure of the ventral mesentary?
This divides the ventral mesentery into 2 parts:
Falciform ligament
Lesser omentum
The mesoderm on the surface of the liver differentiates into visceral peritoneum except on what ?
the cranial surface
The cranial surface remains in contact with the septum transversum and becomes the ________?
bare area of the liver
Around margins of bare area, peritoneum reflects to form the ________?
coronary ligament
Coronary ligament ultimately ends at the lateral edges of the liver as the left and right _________?
triangular ligaments
What percentage of total body weight is the liver at 10 weeks?
10%
What percentage is the liver of total body weight at birth?
5%
Why is the liver so large in the foetus?
it’s importance in haematopoiesis
Where does haematopoisis shift to after birth?
the bone marrow
What does a ventral outgrowth of the bile duct form at the end of week 3?
the gallbladder and cystic duct
At what week does the liver start to produce bile?
week 12
What is the first dark green bowel movement o a newborn called?
meconium
Why are 60% of full term infants jaundiced?
The immature liver does not have sufficient glucuronosyltransferase to conjugate bilirubin
What is kernicterus and how is it treated
Excess unconjugated bilirubin crosses the blood-brain barrier and causes brain damage
Phototherapy oxidises bilirubin to a water soluble form that can be easily excreted by the newborn and does not contribute to kernicterus
(Blue light)
What does failure of either duct to recanalise lead to?
biliary atresia
How common is biliary atresia?
1 in 15,000 births
What are the symptoms of biliary atresia?
Causes symptoms that are initially indistinguishable from neonatal jaundice but do not respond to phototherapy
How are multiple gallbladders caused? (2 or 3)
Caused by extra endodermal outpocketing during weeks 5 and 6
The dorsal bud appears in week __ as an outpocketing of the duodenum that extends into the _______ _______.
The dorsal bud appears in week 3 as an outpocketing of the duodenum that extends into the dorsal mesentery
As duodenum rotates ___ clockwise (as stomach rotates) the ventral bud carried _____ along with bile duct
As duodenum rotates 90° clockwise (as stomach rotates) the ventral bud carried dorsally along with bile duct
During what week do the ventral and dorsal pancreatic buds fuse?
week 6
What does the ventral pancreatic bud form?
Uncinate process
At which point does the main pancreatic duct enter the duodenum?
at major duodenal papilla (Ampulla of Vater)
Where does the accessory pancreatic duct enter?
minor duodenal papilla
What are the implications of a bilobed pancreatic bud migrating dorsally to surround the duodenum
This can compress the duodenum causing gastrointestinal obstruction
Where can ectopic pancreatic tissue be found?
Can be found in areas ranging from distal oesophagus to tip of primary intestinal loop.
Most frequently in duodenum or stomach mucosa
What are symptoms of ectopic pancreatic tissue?
asymptomatic
Large lesions may cause obstruction, ulceration or haemorrhage
What layer is the spleen derived from?
mesoderm
